Many methods are currently known to rehabilitate or repair existing pipe junctions. For example, a cured-in-place pipe liner may be used to rehabilitate a pipe junction. Cured-in-place pipe liners are commonly used throughout the pipelining industry, and there are two common forms of cured-in-place pipe lining methods that have been used for the repair of the junction of a main and lateral sewer pipe. One cured-in-place system and method commonly used for the repair of such a junction is a brim-style junction liner, commonly referred to as a “top hat” system. This method of repairing a junction includes the use of a tubular pipe liner within the lateral portion of the junction, and the use of a flange or brim within the main portion of the junction. Examples of brim-style junction liner systems and methods are found in U.S. Pat. Nos. 5,393,481; 6,337,114; and 6,899,832.
A brim-style junction liner generally relies on adhesion to create a seal at the junction of a lateral and main pipe, as a curable resin is impregnated into the pipe liner and the impregnated liner is allowed to cure against the walls of the junction. The structural integrity of the lateral portion of the junction liner will remain intact for a long period after installation, as the tubular form will conform to the interior of the lateral pipe and provide reinforcement to the existing structure. However, there is nothing to ensure the structural integrity of the brim portion, as it only conforms to a portion of the main pipe interior proximal to the junction, relying on an adhesive bond with the host pipe to ensure the integrity of the seal. There are no features in the currently available brim-style junction liner systems preventing the flange portion of the liner from detaching from the main pipe and breaching the seal created during the lining process.
The second cured-in-place system and method commonly used for the repair of a junction is where the cured-in-place pipe liner includes a tubular lateral pipe liner within a portion of the lateral pipe and a tubular pipe liner within the full circumference of the main pipe. Patents directed at these systems include U.S. Pat. Nos. 5,950,682; 6,039,079; 6,105,619; and 6,994,118. There are many advantages to using such a system, including enhanced structural properties around the junction, decreased risk of junction renewal failure, and enhanced sealing properties. However, because the portion of the pipe liner in the main pipe covers circumference substantial portion of the main pipe, there may be a chance of flow disruption within the main pipe near the junction with the lateral pipe in certain embodiments of the system. Additionally, the resins used in cured-in-place pipelining are subject to polymerization shrinkage, increasing the risk of the seal being breached after installation within the pipe junction.
Accordingly, there is a need in the art for an improved pipe liner assembly for a pipe junction that overcomes the problems of inadequate sealing area and inadequate attachment to the junction to be sealed, while minimizing the chances of flow disruption in the pipeline and creating a fluid-tight seal.